1. Field of the Invention
The present invention relates to a rotary press having a guide roller or rollers for guiding paper from a printing section into a drier disposed downstream of it, and in particular is applicable to such a rotary press that performs perfect printing. The invention is further applicable to a multiweb type rotary press in which a plurality of continuous papers or webs are printed in parallel to one another with a plurality of printers and the printed papers or webs are then laid one on top of another to form a product from them.
2. Description of the Prior Art
A continuous paper or web printed by a rotary press cannot be wound onto a guide roller or the like before the printing ink on it is dried through a dryer to prevent ink transfer. For this reason, it has been customary that such a drier is disposed directly downstream of a printing unit in the rotary press.
In a rotary press that performs perfect printing, e.g., a vertical offset rotary press having a plurality of groups of B—B (blanket-blanket) printing cylinders vertically disposed, however, where the dryer is mounted horizontally on a floor surface for the convenience' sake of the space in which it is disposed, there arises the need to guide each printed paper to the inlet of the drier by means of a guide roller or the like. But it could then be unavoidable that a printed paper surface which remains undried may come into contact with a guide roller surface, causing the ink from a print to adhere on the guide roller and then to remove or transfer back to a paper surface, thereby contaminating the printed paper or print. Therefore, a means is made necessary that prevents ink from transferring from the undried printed paper surface onto a surface of the guide roller disposed downstream of the printing section.
The conventional ink transfer preventing measure of this type is to have an ink transfer preventive sheet wound on the surface of such a guide roller (see, e.g., JP S53-7841 B and JP H11-20134 A) or to cool ink on the paper surface with a roller whose surface is cooled (see, e.g., JP H06-182963 A). To prevent ink transfer, a measure has also been known that guides the printed paper non-contactually while blowing air from the guide surface of a guide bar such as a non-rotating turn-bar (see, e.g., JP H08-245028 A).
While the conventional guide roller having the ink transfer preventive sheet wound thereon is capable of limiting the ink transfer onto the guide roller surface, it cannot eliminate the same completely and requires the guide roller surface to be washed periodically. Also, the means that cool the undried ink on the paper surface for preventing the ink from transferring to a downstream roller requires a special makeup for cooling the roller, and hence become costly. Further, the aforementioned measure of guiding the paper non-contactually requires a special makeup for blowing air, and here again becomes costly. Furthermore, with the paper surface floated by air, this measure presents the problem that the paper fluctuates in tension and its registration is not steadied.
That a drier is disposed immediately downstream of a printing unit is true for a multiweb type rotary press system as well in which a plurality of continuous papers or webs are printed side by side with a plurality of printers and after they are printed are laid one on top of another to form a product from them. In such a rotary press system as shown in FIG. 1, rotary presses 5a, 5b each of which comprises a paper feeder 1, a printing unit 2, a drier 3 and a cooler 4, and whose number corresponds to the number of webs 6 are disposed in parallel with one another. The webs 6 printed are laid one on top of another with an inverting unit 7a, 7b using a plurality of guide rollers and turn-bars each disposed downstream of the cooler 4 in each of the rotary press 5a, 5b, and thereafter are allowed to travel via various guide rollers into a working and a processing section comprising a cutting and a folding unit and so on.
In order to circumvent the problem that not only is a large space required but also both the operability and controllability of the system become poor if the rotary presses 5a, 5b are disposed in parallel on a floor as mentioned above, JP H07-227952 A describes a rotary press as shown in FIG. 2 in which in conjunction with a plurality of paper feeders 1a, 1b disposed in series with one another a plurality of printing units 2a are disposed one above another. Disposed downstream of these printing units 2a, 2b are a dryer 8 through which webs 6, 6 printed through the respective printing units 2a, 2b are passed in parallel to dry the printing ink thereon simultaneously and a cooler 9 through which the webs 6, 6 with the ink dried are cooled.
While the abovementioned makeup having a plurality of printing units disposed one above another is less disadvantageous than that of the horizontal parallel type not only in terms of the space of its installation on the floor but also in its workability and operability, there is presented the problem anew that the size is enlarged vertically.
Further, where printing units placed one above another comprise printing cylinders to be exchanged to meet with a change in printing size, it becomes troublesome to make an exchange for an upper printing cylinder because of a raised position of its exchange and an increased distance from its storage position to the raised position where it is worked on for replacement.